Hard disk drives are enclosures in which an inflexible platter coated with magnetic material is rapidly spun. A magnetic read/write head “flies ”only a few microns above the disk on an air cushion. To provide a hard disk drive having high efficiency, it is generally desirable to position the head as close to the disk as possible without touching it.
Particulate and gaseous contaminants act to reduce efficiency and longevity of hard disk drives. Common sources of contaminants in disk drives include leaks (which may or may not be intentional), the manufacturing environment, and the materials incorporated into the disk drive which give off particulates and gases. Organic vapors can be generated inside disk drive enclosures during normal operating conditions when, for example, the temperature exceeds 150° F. (about 65° C.). Such temperatures can be achieved by simply leaving the computer in the trunk of a car on a hot day.
As aerial densities of disk drives continue to increase and flying heights become smaller, disk drives are becoming increasingly sensitive to moisture, chemical contamination and particulate contamination. Chemical contaminants include hydrocarbons that can condense onto the disk and degrade the head/disk interface, and acid gases that can corrode the heads. Particulate contamination can lead to stiction of the drive head, causing read/write errors, and head crashes.
A typical method to reduce the level of contamination inside a drive is to seal the drive so that outside contaminants cannot enter. However, manufacturing methods available today make it difficult to adequately seal the drive at a reasonable cost. An alternative is to reduce leaks throughout the drive and create a breather hole in the exterior of the drive enclosure for air to enter and exit the drive during the heating/cooling cycles caused by the drive's operation. Typically a breather filter is then positioned over the breather hole to prevent contaminants from the outside from reaching the interior of the drive enclosure. Frequently, a recirculation filter is also utilized in an electronic enclosure to adsorb and/or absorb contaminants that originate within the electronic enclosure.
Therefore, a need exists for an economical filtering solution to the problems that are currently addressed by separate breather and recirculation filters.